1. Field of the Invention
The present invention relates to a method used in a wireless power system, and more particularly, to a method of identifying a wireless power receiver in a wireless power system.
2. Description of the Prior Art
With the proliferation of portable electronic devices such as mobile device (MD), smart phone and tablet PC, the demand for charging devices, especially for those provided in public areas, is increasing. In addition, people would like to get rid of annoying wires if possible. One technology which realizes this desire is wireless charging, in which portable electronic device(s) comprising a wireless power receiver is placed on and charged through a wireless power base station (e.g. a power base station comprising a wireless power transmitter).
Wireless Power Consortium (WPC) is a leading organization in the world in defining wireless charging specification. The document ‘Wireless Power Transfer—Volume I, part I’ in version 1.1.2 released in June 2013 describes an inter-operability interface between a wireless power transmitter (PTX) and a wireless power receiver (PRX).
Currently, the WPC is starting to define a new wireless power standard based on resonant technology, which is also known as Out-of-Band communication technology, wherein a communication interface based on the technologies with higher data rate such as Bluetooth Low Energy (BLE) and Near Field Communication (NFC) is discussed. Among the two candidates, the BLE can reach one Mbps data rate and the NFC can have four hundred Kbps data rate, which implies more applications become possible if such Out-of-Band communication technologies are adopted.
Communication interface is critical due to the need to exchange information between the wireless power transmitter and the wireless power receiver. However, since the Out-of-Band communication technology is not based on modulation of wireless power signals, a mismatch issue, or cross connection, shall be considered. Actually, such mismatch issue is already existed in another standard defined by Alliance for wireless power (A4WP), in which the communication interface between the wireless power transmitter and the wireless power receiver is based on the BLE.
Specifically, please refer to FIG. 1, which is a schematic diagram of a wireless power system 10. The wireless power system includes two wireless power base stations 120 and 140 and two mobile devices 100 and 130. The wireless power base station 120 is supplying power to the mobile device 100 while the wireless power base station 140 is supplying power to the mobile device 130 (denoted with a blank arrow). There shall be a communication interface between the wireless power base station 120 and the mobile device 100, which allows the wireless power base station 120 to get feedback information, such as the amount of power received, from the mobile device 100. However, in some cases the mobile device 100 mistakenly connects to the wireless power base station 140 instead of the wireless power base station 120 (denoted with a dashed arrow). On the other hand, the mobile device 130 which shall connect to the wireless power base station 140 now connects to the wireless power base station 120. In other words, the mobile device 100 connects to (and thus communicates with) the wireless power base station 140 which is not the wireless power base station 120 supplying power to this mobile device 100. It is indeed a mismatch and both the wireless power base stations 120 and 140 cannot identify the mobile devices 100 and 130 to which they are supplying power to get correct feedback information from the mobile devices 100 and 130. Due to the mismatch, the information sent from either the wireless power base station or the mobile device may go to wrong destination. For example, the wireless power base stations 120 and 140 may provide wrong, e.g. excess or deficient, charging power to the mobile devices 100 and 130.
Therefore, there is a need to implement identification mechanism between the mobile device and the wireless power base station to solve the abovementioned issue.